Outgoing call disconnect

hn4498

I have the problem that the calling only maintain 1-2 minutes, then disconnect.

My configruation is:
China: Obi110  + local fixed line
Hong Kong: Obi202 + ObiLINE + local fixed line
Macau: Obi202 + ObiLINE + local fixed line
Add each Obi ID into speed dial which can dial:
2* +phone ==> ring to China
3* +phone ==> ring to HK
4* +phone ==> ring to Macau

Symptom:
China call to HK mobile or Macau mobile, disconnect within 1 minute
HK call to Macau mobile, disconnect within 1-2 minutes
Macau call to HK, disconnect within 1-2 minutes

Any Ching has this experience?